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Minute glands, of a reddish or purplish color, thickly cover the upper surface of the leaf, excepting towards the margins, the rest of the leaf being green. No glands are found upon the spikes or upon the foliaceous footstalk. From twenty to thirty polygonal cells, filled with purple fluid, constitute each gland. They are convex above, somewhat flattened underneath, and stand on very short pedicels, into which spiral vessels do not enter. They have the power of secretion under certain influences, and also that of absorption. Minute octofid projections, of a reddish-brown color, are scattered in considerable numbers over the footstalk, the backs of the leaves and the spikes, with a few on the upper surfaces of the lobes.

The sensitive filaments, which are a little more than one-twentieth of an inch in length, and thin, delicate and tapering to a point, are formed of several rows of elongated cells, filled with a purplish fluid. They are sometimes bifid or even trifid at the apex, and towards the base there is a constriction formed of broader cells, and beneath the constriction an articulation, supported on an enlarged base, consisting of differently shaped polygonal cells. As the filaments project at right angles to the surface of the leaf, they would have been in danger of being broken off whenever the lobes closed together had it not been for the articulation, which allows them to bend flat down. So exquisitely sensitive are these filaments, from their tips to their bases, to a momentary touch, that it is hardly possible to touch them even so lightly or quickly with any hard object without causing the lobes to close, but a piece of delicate human hair, two and a-half inches in length, held dangling over a filament so as to touch it, or pinches of fine wheaten flour, dropped from a height, produce no effect. Though not glandular, and hence incapable of secretion, yet the filaments by their sensitiveness to a momentary touch, which is followed by the rapid closure of the lobes of the leaf, assure to Dionæa the necessary supply of insect food for all its wants.